Engine starter drive



March 7, 1950 D. L.. MILLER 2,500,133

ENGINE STARTER DRIVE Filed sept. s, 1949 l Jy IN V EN T06.

Patented Mar. 7, 1950 ENGINE STARTER DRIVE Donald L. Miller, Elmira, N.Y., assignor to Bendix Aviation Corporation, a corporation of Dela- WareApplication September 3, 1948, Serial No. 47,638

2 Claims. p 1

The present invention relates to an engine starter drive, and moreparticularly to starter gearing of the type which automatically connectsthe starting motor to an engine gear when the starting motor isenergized, and disconnects the starting motor when the engine starts.

It is an object of the present invention to provide a novel enginestarter drive which is efficient and reliable in operation, simple inconstruction, and economical to manufacture.

It is another object to provide such a device 4which incorporates asmall number of parts, and is easily assembled.

It is another object to provide such a device in which the parts whenassembled, are not sub-` ject to displacement or loss of adjustment inuse.

The present invention is an improvement on the structure shown in Fig. 4of applicants prior application, Serial No. 756,464 filed June 23, 1947,now Patent No. 2,481,324, and concerns especially the stop means whichdefines the operative position of the drive pinion.

Further objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawing in which:

Fig. l is a side elevation partly broken away and in section of apreferred embodiment of the invention;

Fig. 2 is a similar View showing the parts in cranking position; and

Fig. 3 is a detail in perspective of the screw shaft with the integralstop means for the nut formed thereon.

In Fig. 1 of the drawing there is illustrated a power shaft I on which ascrew shaft 2 is xedly mounted as by means of a cross pin 3 retained bya lock ring 4.

A pinion 5 is slidably journalled on the power shaft I for movement intoand out of mesh with an engine gear 6. Means for traversing and rotatingthe pinion from the screw shaft ig provided comprising a nut member 8threaded on the screw shaft 2 and having a splined connection asindicated at 9 with one end of a barrel II. The opposite end of thebarrelY II is rigidly connected as indicated at I2 to a driving overloadrelease clutch member I3 which is journalled on an extension I4 of thepinion against a washer I5 which abuts a shoulder I6 formed by reducingor turning down the teeth of the pinion.

A driven slip clutch member I1 is splined on the hub I4 of the pinion 5as indicated at I8, and is pressed against the driving clutch member I3by yielding means here shown in the form of an elastic washer I9 whichis retained on the end of the pinion hub by means of a lock ring 2 I.

Means normally holding the pinion 5 and barrel I I in extended relationwith respect to the nut 8 is provided in the form of a compressionspring 22 within the barrel bearing at one end against the nut 8 and atits other end againsta thrust washer 23 which is fixed in the barrel bya lock ring 24. The nut 8 is retained within the barrel by a splitthrust ring 25.

Means normally maintaining the parts in idle position are provided inthe form of an anti-drift spring 26 bearing at one end against the nut 8and at its other end against a thrust ring 21 seated on the end of thescrew shaft 2.

As best shown in Fig. 3, the screw shaft 2 is formed with a radialflange to limit the travel of the nut 8 toward meshing position. Thethreads of the screw shaft are milled right through the flange so as toleave radial lugs 28, 29 and 3| which arrest the movement of the nut 8when the pinion is in meshed position, a thrust washer 32 beingpreferably interposed therebetween. The lugs 28, 29 and 3| are turneddown for a short distance to provide shoulders 33, 34 and 35 againstwhich the thrust ring 21 seats.

The driving overload release clutch member I3 is provided with inclinedtorque transmitting teeth 36, and the driven clutch member I1 isprovided with corresponding teeth 31 which are pressed together by thespring washer I9 so as to transmit torque from the barrel to the pinion.When a predetermined load is exceeded. the teeth 36, 31 wedge themselvesapart against the action of the spring washer I9 and slip off theoverload until normal conditions are established.

In operation, starting with the parts as illustrated in Fig. l, rotationof the power shaft I and screw shaft 2 causes traversal of the nut 8with its associated parts to cause the pinion 5 to mesh with the enginegear 6. The longitudinal travel of the nut 8 is limited by abutment ofthe nut against the thrust washer 32 which accordingly defines themeshing position of the pinion by its abutment against the radial lugs28. 29, 3| of the screw shaft. The clutch I3, I1 is preferably so loadedby the spring washer I9 that the initial shock caused by engagement ofthe pinion with the engine gear is cushioned by slippage of the clutch.After cranking has started, it ordinarily proceeds without slippage ofthe clutch unless a backfire of the engine should cause resistance tocranking to exceed the predetermined maximum, in which case the clutchwill again slip in order to cushion the drive..

If tooth abutment between the pinion 5 and engine gear 6 should occurduring the meshing movement of the pinion, spring 22 yields and permitsthe nut 8 to proceed along the screw shaft 2 until the driving torquebuilds up sufiiciently to index the pinion teeth into proper registrywith the tooth spaces of the engine gear, after which serieel? expandsemifelep the pinion into mesh, whereuponrcranking `proceeds as usual.

When the engine res, the parts are returned design arid-arrangement' efthe parts Witheet elepertine time; ilse'egirt clalm' ,e starter-drive@pewereheft e Se eW- .Sheft 'xes meteen, e vivier-1 Slideblv xeurinalleelOnthe newer shaft for movement wie and eilt of meel; with @seeref enginete be started, a control nut threaded on the screw shaft, a drivingclutch member swiveled on the pinion, a barrel member non-rotatablyconnected at its ends to the nut and driving clutch member, a drivenclutch member splined on the pinion, yielding means holding the clutchmembers in engagement, yielding means transmitting longirtudinalmcveyient from thev nut to the barrel, and.rneanspositivelyconninglthe nut inathe barrel,

thev threads of said screw shaftv having radial 4shoulders in the sameplane transverse to the axis of the drive, forming a stop for thecontrol v`n'ut'to thereby dene the fully meshed position providing saiddstop shoulders for the control nut.

DONALD L. MILLER.

REFERENCES CITED eine ,following refererieeeam e? '.lfeeerd @il the@ieu-0i this :intenti "UWTED STATE@ BATENTS Date Name

Number

